Removable weights have been incorporated into golf club heads to distribute discretionary mass in order to alter the performance characteristics of the golf clubs. For example, weights may be incorporated to provide adjustability in characteristics such as swing weight, location of the center of gravity and manipulation of the moment of inertia of a particular golf club head. Various weight designs have been utilized that allow the manufacturer and/or consumer to alter the mass properties of a golf club head.
One example of a weight incorporated into a club head is described in U.S. Pat. No. 1,167,106 to Palmer for a Golf Club. Palmer describes a golf club that includes a threaded opening that receives threaded weight plugs for varying the weight of a cast metal golf club head. The threaded opening extends through a rear wall of the golf club head and receives a threaded plug which may be just long enough to fill the opening or it may extend further into the golf club head to increase the weight. The threaded opening is tapered so that the plug may be tightened to a desired depth. A disadvantage of the threaded weight plug is that it is constructed as a single piece. As a result, torque applied to the weight plug during use of the golf club is transmitted to the threaded portion and may result in the weight plug becoming disengaged, especially with repeated use.
Another example of a removable weight is described in U.S. Pat. No. 6,773,360 to Willett et al. for a Golf Club Having a Removable Weight. The removable weight includes a mass element and a fastener that extends through an aperture in the mass element. A golf club head body includes an interior cavity and a recess on a wall of the body. Inside the recess, a threaded opening is provided so that the fastener may extend through the mass element disposed in the recess and into the threaded opening to fasten the mass element in the recess. Because the fastener extends through the mass element and into a threaded opening in the recess, the size of the mass element and the structure of the recess are limited. Additionally, the mass element is visible to the user when installed so less variation is available for the mass element without detrimentally affecting the aesthetics of the club head.
It is desirable to provide a golf club head and a weight member that allows additional design freedom for the weight while creating fewer restrictions on the golf club head design.